# FLUID MECHANICS : IMPORTANT QUESTIONS/ANSWERS

Q1.) What is Fluid Mechanics?

Ans. Fluid mechanics is the branch of physics concerned with the mechanics of fluids (liquids, gases, and plasmas) and the forces on them. It has applications in a wide range of disciplines, including mechanical, civil, chemical and biomedical engineering, geophysics, oceanography, meteorology, astrophysics, and biology.

Q2.) Why is a force exerted by a static fluid on a surface always perpendicular to the surface?

Ans. The force of gravity is always acting on all objects with mass. Our weight on Earth is due to gravity and it is acting vertically downwards. The fluid has mass and it is also pulled by gravity vertically downwards. As per Newton’s laws, the action and reaction are equal and opposite in nature. The fluid resists the downward pull on it by gravity. So it exerts upwards force vertically opposite to that of gravity. That is why the force exerted by fluid at static is always perpendicular to its surface.

Q3.) What is computational fluid dynamics?

Ans. Computational fluid dynamics is a branch of fluid mechanics that uses numerical analysis and algorithms to solve and analyze problems that involve fluid flows. High-speed supercomputers are used to perform the calculation that is required to simulate the interaction of liquids and gases.

Q4.) What are the Applications of fluid Dynamics?

Ans. Fluid Dynamics can be applied in the following ways:

•  Fluid dynamics is used to calculate the forces acting upon the aeroplane.
• It is used to find the flow rates of material such as petroleum from pipelines.
•  It can also be used in traffic engineering (traffic treated as continuous liquid flow).

Q5.) Why mercury rather than water is used in barometers?

Ans. Mercury is commonly used in barometers because its high density means the height of the column can be a reasonable size to measure atmospheric pressure. A barometer using water, for instance, would need to be 13.6 times taller than a mercury barometer to obtain the same pressure difference.

Q6.) Why is it difficult to swim under water in the Great Salt Lake?

Ans. Because the salinity of the water is very high.salt increase the overall mass of the water and makes the water become denser than (less strayed particle) Compared to normal salt. Objects float better on a dense surface (less strayed particle). Which mean that when you swim on the salt water, it would be hard for you to stay submerged under the water.

Q7.) Is there a net force on a dam due to atmospheric pressure?

Ans. Atmospheric pressure is on both sides of the dam, so this atmospheric pressure cancels out. Therefore is no net force on dam due to atmospheric pressure.

Q8.) What is Pascal's Law?

Ans. Pascal's law is a principle in fluid mechanics that states that a pressure change at any point in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere.

Q9.) What do you understand by Archimedes Principal?

Ans. Archimedes' principle also called as Law of buoyancy which states that " An object immersed in a fluid experiences a buoyant force that is equal in magnitude to the force of gravity on the displaced fluid".

Q10.) How can be define Bernoulli's Theorm in fluild Dynamics?

Ans. In fluid dynamics, Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluid's potential energy.